| Year | Value | | 2022 | 51.084164137337 | | 2021 | 50.55324972691 | | 2020 | 50.228987392195 | | 2019 | 50.282218294092 | | 2018 | 50.795007499733 | | 2017 | 48.884636556659 | | 2016 | 46.842035758057 | | 2015 | 46.242306733988 | | 2014 | 44.04949187777 | | 2013 | 42.452499086521 | | 2012 | 43.357714069196 | | 2011 | 41.798266062685 | | 2010 | 41.149496655001 | | 2009 | 39.527493963691 | | 2008 | 38.955691632334 | | 2007 | 36.697589153876 | | 2006 | 34.597562583586 | | 2005 | 34.507925398565 | | 2004 | 33.73946917765 | | 2003 | 34.110951343532 | | 2002 | 35.620125989429 | | 2001 | 35.702767473581 | | 2000 | 38.148721465242 | | 1999 | 43.203851134402 | | 1998 | 44.076870245553 | | 1997 | 44.245851768962 | | 1996 | 44.804213516393 | | 1995 | 47.927581459706 | | 1994 | 48.349214930858 | | 1993 | 49.676496461789 | | 1992 | 50.449746537301 | | 1991 | 51.334354080532 |
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